Earth's second sun

Earth has already a second moon, but a second sun is impossible. Right? Not quite.

In the constellation of Orion, Betelgeuse forms the left hand shoulder of the warrior (see the sword dangling from his belt). It is a red giant, a semi-regular variable star in the latter stages of its life whose apparent magnitude varies between 0.0 and 1.3. Which is a lot.
As Betelgeuse is using up the last of its fuel, it will become increasingly unstable over time and will eventually collapse due to its own gravity. Then Betelgeuse will become a supernova. Supernovae can outshine the whole galaxy they live in. Supernovae have a 'rising time' of about a week, when the star is increasing in brightness. It stays at its peak brightness for several days days and then slowly declines into obscurity over a period of a couple of weeks. At its point of maximum brightness it can compete with the brightness of a full moon (-11 magnitude). Because Betelgeuse is a star it will become a second sun. Our second sun.

Will we ever live to see such a spectacle in the heavens? Scientists have calculated that the possibility of Betelgeuse imploding and exploding is somewhere between nil and a million years. As Betelgeuse lives a mere 640 light years away from earth, it might already have gone supernova 640 years ago.

So, keep watching the southern sky (if you live in the northern hemisphere).

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